Method for manufacturing disposable rotary cutting tools and disposable rotary tool for dental or medical applications

ABSTRACT

The shank ( 12 ) of a disposable rotary cutting tool ( 10 ) comprises a pipe section ( 16 ) cut from a drawn metal pipe. The tool head ( 14 ) is formed from a cut-out ( 18   a,    18   b ) of a drawn metal sheet or a section of a metal tube by non-cutting machining. The pipe section ( 16 ) and the tool head ( 14 ) are advantageously attached by force fitting.

FIELD OF THE INVENTION

The present invention relates to a method for manufacturing disposablerotary cutting tools for dental or medical applications and a disposablerotary cutting tool for dental or medical applications.

BACKGROUND

There are a large number of cutting tools on the market for variousapplications in the medical or dental field, in particular forapplications involving drilling, tapping, milling, smoothing, formingand other cutting functions in a bone or a tissue. For example, in thedental field, drills are used for drilling holes in the jawbone. A tapis then used, and perhaps also a profiling tool, so that an anchoringsupport can be screwed in order to fix a tooth crown. In the medicalfield, profiling, smoothing and milling tools are used in order todrill, profile or smooth the bony material or to remove deposits.

Most of the cutting tools available on the market are tools made fromsteel of medical quality, which are manufactured at least partially bymachining with removal of chips. These tools generally being made formultiple use, inter alia on account of their relatively highmanufacturing costs. There is, however, an increasing demand and fordisposable tools, i.e. for once-only use, on account of the risks of thetransmission of diseases, but also because of the costs of thesterilization of reusable tools.

RU-C-2 167 618 discloses a disposable needle-type drill for bone tissue.The drill comprises a casing made in the form of a tube or continuos rodwith a flat or square portion. A front working part of the drill isprovided with cutting members formed as longitudinally arranged needles.This known drill may be used for performing operations in traumatology,neuro-surgery etc.

Drills for the insertion of dental implants, that can be disposed ofafter each use, are disclosed in U.S. Pat. No. 5,839,897. The drillincludes a rotational drive portion in the form of a metal rod with afirst end and a second end. The first end is intended to be connected toa drilling apparatus. The second end is connected to an active cuttingportion made of plastic overmolded on the second end of the metal rod.The drill further includes a metal insert portion coupled to the activecutting portion to serve as a sharp edge for the active cutting portion.

The disposable rotary cutting tools disclosed in these prior artdocuments comprise parts being injection-molded or complexly machinedand not making it possible to carry out simple modifications of the toolfor different applications. Further more, plastic parts for such toolsare usually not readily accepted in invasive applications because of therisks of breakage of the plastic and of the deposit of plastic particlesduring the surgical operation.

SUMMARY OF THE INVENTION

According to one or more embodiments of the present invention, a methodis provided for manufacturing disposable rotary cutting tools for dentalor medical applications in large series at low cost. According to otherembodiments, low cost disposable rotary cutting tools are provided fordental and medical applications that are reliable and safe.

The term “cutting tool” is used to refer, in general, to all rotatingtools making it possible to work the bone or tissue by cutting or byabrasion for various functions, such as drilling, milling, smoothing andprofiling of, more particularly, a bone, but also a tissue.

According to one embodiment, at least a part of a shank of the tool isformed from a pipe section cut from a metal pipe. A tool head is formedfrom a metal sheet or tube. The tool shank and the tool head aremanufactured separately and assembled together.

Advantageously, the modular construction of the tool for once-only useaccording to this embodiment allows a high degree of versatility in themanufacture of different tools, in that, for example, simply the toolhead and/or the tool shank is/are changed. Producing at least a part ofthe tool shank in the form of a pipe section is highly advantageous interms of the manufacturing costs in large series. On the other hand, itmakes it possible to assemble the tool head and the tool shank by meansof simple operations, such as driving in, while at the same timeensuring good mechanical resistance and the absence of the use ofplastic in the invasive part of the tool.

A further working of the pipe section, for example by drawing, swagingor stamping, is advantageous in a high volume fabrication.

To detach a cut-out from a metal sheet or a tube section from a metaltube by non-cutting machinery and the forming of the tool head bynon-cutting machinery, in particular by punching, swaging or stamping,is inexpensive and generates at the same time the sharp edges fortreating the bone or tissue.

Drawn metal pipes, metal sheets and metal tubes are especially wellsuited for manufacturing the tool shank and the tool head.

Driving the pipe section of the tool shank and the tool head into oneanother in order to assemble them and especially a force fitting isadvantageous from the point of view of the manufacturing costs, while atthe same time ensuring high mechanical resistance and therefore safetyagainst the risk of breakage of the tool.

In a further preferred embodiment, the pipe section may be equipped witha small cut-out monitoring window, thus making it possible to take asample of the drilled bone or tissue or to ascertain whether the toolhas already been used or not.

For some applications, the tool head my be formed from more than onecut-out forming blade. Where a plurality of cut-outs are concerned, thecut-outs are advantageously equipped with complementary slots in orderto be inserted one into the other and driven into the pipe section.

Further advantageous characteristics may be gathered from the followingdescription and from the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a plane view of a first cutting tool according to anembodiment of the invention, this tool being used for drilling holes toa depth determined by a stop provided for this purpose;

FIG. 2 is a longitudinal sectional view of the first cutting tool;

FIG. 3 is an exploded perspective view of the first cutting tool;

FIG. 4. is a perspective view of the first cutting tool;

FIG. 5 is a plane view of a second cutting tool according to anotherembodiment, this tool being used for drilling annular ducts and fortaking samples of tissue or bone;

FIG. 6 is a longitudinal sectional view of the second cutting tool;

FIG. 7 is an exploded perspective view of the second cutting tool;

FIG. 8 is a plane view of a third cutting tool according to anotherembodiment, this tool being used for drilling operations;

FIG. 9 is a longitudinal sectional view of the third cutting tool;

FIG. 10 is an exploded perspective view of the third cutting tool;

FIG. 11 is a plane view of a forth cutting tool according to anotherembodiment, similar to the third cutting tool;

FIG. 12 is a longitudinal sectional view of the fourth cutting tool;

FIG. 13 is an exploded perspective view of the fourth cutting tool;

FIG. 14 is a plane view of a fifth cutting tool according to anotherembodiment, similar to the third and fourth cutting tools;

FIG. 15 is a longitudinal sectional view of the fifth cutting tool;

FIG. 16 is an exploded perspective view of the fifth cutting tool;

FIG. 17 is a plane view of a sixth cutting tool according to anotherembodiment, which tool is used for drilling operations;

FIG. 18 is a longitudinal sectional view of the sixth cutting tool;

FIG. 19 is an exploded perspective view of the sixth cutting tool;

FIG. 20 is a plane view of a seventh cutting tool according to anotherembodiment, being used as a profiling tool;

FIG. 21 is a longitudinal sectional view of the seventh cutting tool;

FIG. 22 is an exploded perspective view of the seventh cutting tool;

FIG. 23 is a plane view of an eighth cutting tool according to anotherembodiment, being used for drilling operations;

FIG. 24 is a longitudinal sectional view of the eighth cutting tool;

FIG. 25 is an exploded perspective view of the eighth cutting tool;

FIG. 26 is a plane view of a ninth cutting tool according to anotherembodiment, being used as a drilling or chamfering tool or as a tool forforming conical cups in the bone;

FIG. 27 is a longitudinal sectional view of the ninth cutting tool;

FIG. 28 is an exploded perspective view of the ninth cutting tool;

FIG. 29 is a perspective view of the ninth cutting tool;

FIG. 30 is a plane view of a tenth cutting tool according to anotherembodiment, this tool being a tapping tool for making a screw thread;

FIG. 31 is a longitudinal sectional view of the tenth cutting tool;

FIG. 32 is an exploded perspective view of the tenth cutting tool;

FIG. 33 is a longitudinal sectional view of an eleventh cutting toolaccording to another embodiment, this tool being used for formingspherical cups in the bone;

FIG. 34 is an exploded perspective view of the eleventh cutting tool;and

FIG. 35 is a perspective view of the eleventh cutting tool.

DETAILED DESCRIPTION

The first embodiment of a cutting tool 10 shown in FIGS. 1 to 4comprises a tool shank 12 and a tool head 14. The tool shank 12 consistsof a pipe section 16 cut from a drawn metal pipe. The shell of the pipesection 16 is parameterized and branded.

The tool head 14 is formed by two cut-outs 18 of a drawn metal sheet,that are arranged in a crosswise manner. The cut-outs 18 a, 18 b aredetached form the metal sheet by non-cutting machining, for example bypunching. The thereby produced sharp edges are not further machined.

The cut-outs 18 a, 18 b have an essentially rectangular formed workingportion 20 and an adjacent integral rectangular fastening portion 22. Afront edge 24 of the working portion 20 is indeed formed to a vertexwhereby the front edge portions enclose an obtuse angle.

Furthermore, the cut-outs 18 a, 18 b comprise complementary slots 26 a,26 b, i.e. the cut-out 18 a has a slot 26 a running along a central axisof the cut-out 18 a from the front end of the cut-out 18 a to the middleof the cut-out 18 a, and the cut-out 18 b has a corresponding slot 26 brunning from the rear end to the middle. By these slots 26 a and 26 b,the two cut-outs 18 a and 18 b can be retracted one into the other tobuild the tool head 14 with two crosswise arranged blades.

The lateral edges of the working portion 20 of the cut-outs 18 a, 18 brunning in the longitudinal direction comprise four rectangular recesses28. These recesses 28 serve for the immobilization of a stop 30 in theform of an injection-molded plastic ring at a desired position. For thatpurpose, the stop 30 comprises on the inside a bead 32 running in acircumferential direction and having four interrupts 34. If theinterrupts 34 align with the assembled cut-outs 18 a, 18 b, the stop 30can be moved in the longitudinal direction of the tool head to thedesired recesses 28. By rotating the stop 30, the bead 32 comes inengagement with the desired recesses 28 and axial movement of the stop30 is prevented.

In the middle between each of two interrupts 34, the stop 30 comprisesprotrusions 36 constituting limit stops limiting the rotational movementof the stop 30 relative to the tool head 14.

The width of each fastening portion 22 of the cut-outs 18 a, 18 b isdetermined such that the fastening portions 22 of the assembled cut-outs18 a, 18 b can be driven into the central duct 38 to a force fitting.

Finally, the first cutting tool 10 comprises a fastening connector body40 with a cylindrical or conical pin portion 42 that is pressed into arear end region of the central duct 38 of the pipe section 16 to createa firm connection between the fastening connector body 40 and the pipesection 36. The fastening connector body 40 further comprises aconnector portion 44—projecting from the pipe section 16—in the form ofa standardized connector for fastening the cutting tool 10 in a drivedevice. The fastening connector body 40 is advantageously produced byinjection-molding of plastic. However, the fastening connector body 40can be made of other materials such as metal.

A second rotary cutting tool 10, shown in the FIGS. 5 to 7, comprises atubular tool head 14. It is manufactured from a section 46 of drawnmetal tube by creating at the front end a crown of saw teeth 48 bynon-cutting machining, for example by punching. Moreover, the tubesection 46 is cut out or stamped to produce a radial monitoring window50 making it possible to check whether the cutting tool 10 has been usedor not, or to make it possible to take a tissue sample.

The tube section 46 is furthermore stamped, for example by means ofprofiled rollers, to form annular protuberances 52 serving as referencemarks for visualizing the cutting depth.

A bushing 54, for example a section of a further metal tube or of aplastic tube, is inserted into a rear end portion of the tube section46. A pipe section 16 constituting the tool shank 12, is similarlyinserted into the bushing 54. By this, a force-fit connection betweenthe tool head 14, i.e. the tube section 46, and the shank 12, i.e. thepipe section 16, is obtained.

A fastening connector part 40′ is integrally formed with the pipesection for example by die squeezing and/or stamping the pipe section16.

The FIGS. 8 to 10 show a third cutting tool 10 comprising a tool shank12 made of two force-fittingly axially joined pipe sections, a pipesection 16 connected to the tool head 14 and a further pipe section 56.

A comparison of these FIGS. 8 to 10 and the FIGS. 5 to 7 clearly showsthat the further pipe section 56 in FIGS. 8 to 10 is preciselyidentically formed as the pipe section 16 of the embodiment of FIGS. 5to 7.

The pipe section 16 as shown in FIGS. 8 to 10 is manufactured from asection of a drawn metal pipe, whose bore is slightly smaller than theouter diameter of the further pipe section 56.

As the tube section 46 of the tool head 14 of the embodiment shown inFIGS. 5 to 7, the pipe section 16 of the embodiment according to FIGS. 8to 10 comprises a monitoring window 50 and protuberances 52.

The tool head 14 shown in FIGS. 8 to 10 is a swaged and/or stampedcut-out 18 of a drawn metal sheet. The bottom 58 of the cup-like toolhead 14 is cone-shaped and comprises a cutting blade 60 built by abar-like part of the bottom 58 bent out of the conical shape. Thecutting edge is formed by the burr of the cutting blade 60.

The tool head 14 is hat-like attached on the front end region of thepipe section 16 in a force fitting manner.

The design of a fourth cutting tool 10 shown in FIGS. 11 to 13 is justthe same as of the cutting tool 10 accordingly to FIGS. 8 to 10 with theexception that the pipe section 16 comprises in its front end region acircumferential contraction 61 formed for example by stamping, swagingor rolling. The diameter of the tool head 14 is accordingly smaller sothat the outer shell of the tool head 14, when attached to the pipesection 16, is flush with the outer surface of the pipe section 16.

The tool head 14 and pipe section 16 of a fifth cutting tool 10 shown inFIGS. 14 to 16 has accurately the same design as the embodiment shown inFIGS. 8 to 10 and described above. The further pipe section 56,force-fittingly attached to the pipe section 16, has the same design asthe pipe section 16 shown in and described in connection with FIGS. 1 to4. A fastening connector body 40 is plugged with its pin portion 42 inthe rear end region of the further pipe section 56. The fasteningconnector body 40 also comprises the connector portion 44 as shown inFIGS. 1 to 4 having an axial passage 62 capable of being used for eitherdelivery of fluid into the cutting tool or storing tissue or bone wasteremoved during the cutting operation.

A sixth embodiment of the cutting tool 10 shown in FIGS. 17 to 19comprises a further pipe section 56 with an integrally formed fasteningconnector part 40′ of the same design as the pipe section 16 shown inFIGS. 5 to 7. This further pipe section 56 is force fittingly driveninto the pipe section 16 of the same design as the pipe section shown inFIGS. 8 to 10 and 14 to 16 with the exception of the absent monitoringwindow 50.

The tool head consists of two cut-outs 18 a, 18 b with a rectangularworking portion 20 and a rectangular fastening portion 22 with a widthgreater than the outer diameter of the pipe section 16 and the width ofthe working portion 20. Consequently slots 26 a and 26 b of the cut-outs18 a, 18 b allow the cross-wise engagement of the cut-outs 18 a, 18 b asalready described in connection with the embodiment shown in FIGS. 1 to4.

The cut-outs 18 a, 18 b further comprise lateral slots 64 beginning atthe rear end of the fastening portion 22, running in the axial directionof the cutting tool 10 and ending a distance from the front end of thefastening portion 22. When attaching the tool head 14 and the pipesection 16, the wall of the pipe section 16 is inserted into theselateral slots 64.

Also these cut-outs 18 a, 18 b are manufactured by punching a drawnmetal sheet.

A seventh embodiment of the cutting tool 10 shown in FIGS. 20 to 22comprises an identical further pipe section 56 as the cutting tools ofFIGS. 8 to 13 and 17 to 19. The further pipe section 16 shown in FIGS.20 to 24 does not comprise protuberances and a monitoring window; it issimply a section sawn from a drawn pipe.

The tool head 14 consist of two cut-outs 18 a, 18 b with complementaryslots 26 a and 26 b attached in a cross-wise manner. Furthermore, thecut-outs 18 a, 18 b comprise lateral slots 64—as described in connectionwith the FIGS. 17 to 19—for the collet of the wall of the pipe section16. In contrast to the embodiment of FIGS. 17 to 19, the cut-outs 18 a,18 b of the present embodiment comprise a fastening portion 20, theinner part of which—arranged in the duct 38 of the pipe section—islonger than the outer part.

FIGS. 23 to 25 show an eighth embodiment of the cutting tool 10 with afurther pipe section 56 as already known from the FIGS. 8 to 13 and 17to 22. In contrast to the embodiments shown in said Figures, the pipesection 16 of the present embodiment is driven into the further pipesection 56; the diameter of the pipe section 16 is smaller than thediameter of the further pipe section 56. The pipe section 16 comprisescircumferential protuberances 52 and a monitoring window 50 as alreadydescribed.

The two cut-outs 18 a, 18 b of the tool head 14 have the form of a brickand comprise complementary slots 26 a, 26 b to make the cross-wisearrangement possible as well as lateral slots 64 for the wall of thepipe section 16. In contrast to the previously described embodimentswhere the slots 26 a and 26 b are of the same length, in the presentembodiment the length of the slot 26 a is shorter than the length of theslot 26 b. The lateral slots 64 go from the rear end of the cut-outs 18a, 18 b close to the front edge 24 so that in the assembled state thepipe section 16 ends only a small distance from the front edges 24.

It is further noted that at least one of the protuberances 52 isarranged in the lateral slots 64 to give by means of a force fittingstability to the small tongue-like parts of the cut-outs 18 a, 18 barranged radially outside of the pipe section 16.

A ninth embodiment of the cutting tool 10 shown in the FIGS. 26 to 29comprises a pipe section 16 with protuberances 52 and a monitoringwindow 50 similar to that disclosed in FIGS. 8 to 10 and 14 to 16. But,the radial inner edge 66 on the front end side of the pipe section 16 isbeveled.

The cut-outs 18 a and 18 b comprise complementary slots 26 a, 26 b forthe cross-wise arrangement of the cut-outs 18 a, 18 b to the tool head14. The protruding working portions 20 of the cut-outs 18 a, 18 b havethe form of an isosceles triangle with cut basis corners. Seen in theradial direction, the working portions 20 project from the pipe section16 only for a very small amount.

As best shown in FIG. 28, the width of the fastening portions 22 in therear half is smaller than in the front half joining the working portions20. Consequently, a force fitting between the cut-outs 18 a, 18 b andthe pipe section 16 occurs only in the front half of the fasteningportions 22. The introduction of the fastening portions into the pipesection 16 is thereby simplified.

The further pipe section 56 comprises in the front end region acontraction 68 created for example by stamping or swaging. Also thiscontraction 68 simplifies the introduction of the further pipe section56 into the pipe section 16, since the contraction 68 does not build aforce fitting with the pipe section 16. The force fitting is built in aregion following the contraction 68.

A fastening connector body 40, without a passage 62, is driven into therear end region of the further pipe section 56.

The pipe section 16 and the further pipe section 56 of a tenthembodiment of the cutting tool 10, shown in the FIGS. 30 to 32, are ofthe same design as those of the embodiment shown in FIGS. 17 to 19.

As already described in connection with other embodiments also the twocut-outs 18 a and 18 b of the present embodiment comprise complementaryslots 26 a, 26 b. The approximately rectangular working portion 20 withchamfered front corners comprises radially protruding teeth 70 offset inthe axial direction, in order to make it possible to form a screw threadin the bone. In the assembled state the rectangular fastening portions22 of the cut-outs 18 a 18 b are located completely in the duct 38 ofthe pipe section 16.

For most applications, it will be sufficient to have two inserted bladesin the form of cut-outs 18 a, 18 b. It is possible, however, to producecutting tools 10 with three or four inserted cut-outs 18 a, 18 b, 18 c,18 d such as the embodiment shown in the FIGS. 33 to 35. This cuttingtool 10 may be used for machining spherical cups, for example in a bone,or for forming a chamfer at the entrance of a drilled hole. For thatpurpose the working portion 20 of the cut-out 18 a, 18 b, 18 c, 18 d iscircular. A rectangular fastening portion 22 joins the working portion22 whereby the fastening portions 22 of the cut-outs 18 a, 18 b and 18 care of the same axial length whereas the cut-out 18 c is smaller.

The cut-out 18 a comprises only one central slot 26 a beginning at thefront end of the cut-out 18 a. The slot 26 a is in the firstthree-fourths of its length wider than in the last fourth. The cut-out18 b has two slots, a slot 26 a beginning at the front end of thecut-out 18 b, equally wide as the wider part of the slot 26 a in thecut-out 18 a, and a slot 26 b beginning at the rear end and equally wideas the smaller part of the slot 26 a of the cut-out 18 a. The cut-out 18c also comprises two slots, a small slot beginning at the front end anda wide slot beginning at the rear end. The rear slot ends—in theassembled state of the tool head 14—by the closed end of slot 26 a ofthe cut-out 18 b. The cut-out 18 d has only one small slot 26 bbeginning at the rear end of this cut-out. The widths of the slots 26 aand 26 b are chosen such that the cut-outs 18 a and 18 b can beassembled in a 90° position relative to each other and such that thecut-outs 18 c and 18 d can be assembled in a 90° position as well aswith an offset of 45° in respect of the cut-outs 18 a and 18 b.

The assembled tool head 14 is then driven, with the rear end of thefastening portion 22 in front, into the pipe section 16, having the samedesign as that shown in FIGS. 30 to 32. The pipe section 16 is connectedto the further pipe section 56 as already known from previous examples.

The fastening connector portion 40′ of all respective embodiments mayhave an axial passage for the supply of fluid into the duct 38 and tothe tool head 14. The metal parts of all embodiments are preferably madefrom steel of medical quality.

In all disclosed embodiments, the parts of the cutting tools 10 areconnected by force fit. The parts may be likewise be fastened bywelding, for example by ultrasonic welding, bonding or form fit. Thus,it is possible to locally deform assembled parts, for example byapplying a radially inwardly directed force in order to strengthen theforce fit or to create a form fit.

The different embodiments of the cutting tools 10 according to thepresent invention are based on a modular construction system that allowsthe manufacture of a variety of different cutting tools 10 by using arelative small number of different parts.

The invention claimed is:
 1. A disposable rotary cutting tool for dentalapplications comprising: a tubular tool shank comprising a drawn metalpipe section having a uniform diameter over its entire length; a toolhead comprising a drawn metal tube section having a uniform diameterover its entire length, wherein the tool head has a first open end and asecond open end, the first open end of the tool head has a crown of sawteeth forming a circumferential cutting surface, the crown of saw teethhaving the same diameter as the rest of the tool head; wherein thesecond open end of the tool head, opposite the first open end, comprisesa bushing, wherein the tool shank is inserted into the bushing, whereinthe tool head is force fit connected to the tool shank; and a fasteningconnector that is connected to the tubular tool shank.
 2. Cutting toolaccording to claim 1, wherein the tool head is manufactured bynon-cutting machining.
 3. Cutting tool according to claim 2, wherein thefastening connector is formed by deformation of the metal pipe section,in an end region away from the tool head.
 4. Cutting tool according toclaim 1, wherein the metal tube section includes a cut-out or stampedradial monitoring window.